The present invention relates to computer data storage and, in particular, to a network attached data storage system.
A typical computer system includes a processor for executing instructions, a memory for storing the instructions executed by the processor and the results of the execution of instructions, an input peripheral that permits a user to interact with the system (e.g., keyboard, mouse etc.), an output peripheral that also allows a user to interact with the system (e.g., monitor, printer etc.), and a storage peripheral (e.g., disk drive, tape drive etc.) that provides data storage beyond that provided by the memory. In operation, the memory typically contains at least portions of two programs, an operating system program and an application program (e.g., a spreadsheet program). The operating system program provides a number of functions, including functions associated with the management of files, directories of files, and the input and output peripherals associated with computer system.
On a larger scale, computer systems are commonly connected to one another to form computer networks. Common networks include local area networks (LANs) in which the computer systems are networked together are distributed over a relatively small area, such as within an office or a building. Another common network is a wide area network (WAN) in which the computer systems that are part of the network are distributed over a relatively large area. As a consequence, third party communication systems (e.g., telephone and satellite) are commonly required to implement a wide area network.
A fundamental advantage of a computer network is that one computer system can write data to or read data from a memory device associated with another computer system within the network. Typically, the transfer of data from one computer system in a network to another computer system in the network commences with the operating system of the computer system that wants to initiate the transfer data issuing a request that is conveyed over the network communication infrastructure (copper cable, fiber optic cable, radio channel etc.) to the other computer system or systems in the network. The operating system associated with the target computer system (the computer system to or from which data is to be transferred) responds to the request by issuing the appropriate command to the memory device to or from which data is to be transferred. This system for transferring data between computer systems in a network has worked adequately for some time because the network infrastructure was considerably slower in transferring data between the computer systems than the operating system associated with the target computer system differently, the target computer system and, in particular, the operating system of the target computer system was capable of causing data to be transferred to other computer systems in the network at a speed that substantially utilized the available bandwidth of the network infrastructure.
Recently, however, the bandwidth or speed of network infrastructure has increased dramatically. As a consequence, the network infrastructure is no longer the slowest element in the transfer of data between one computer system and another computer system in a computer network. Instead, the target computer system and, more specifically, the operating system of the target computer system has become the slowest element. To elaborate, because the operating system associated with the target computer system is typically processing requests from one or more application programs running on the system, managing the peripherals, and performing other tasks, the operating system can only devote a portion of its time to processing data transfers with other computer systems in the network. Further, the time that the operating system can devote to such transfers is now, usually insufficient to fully utilize the bandwidth or speed at which the network infrastructure is capable of transporting data.
As a consequence of the operating system limitation associated with transferring data between computer systems in a network, a new type of storage system or device has evolved, namely, a network attached storage device. A network attached storage system or device has its own address on the network and is, therefore, directly accessible by the other computer systems in the network. Consequently, when a computer system in a network needs to transfer data to or from a network attached storage device, there is no need to go through an operating system associated with another computer system that is busy processing requests from application programs, peripherals and the like.
The present invention is directed to a network storage attached system or device that, in one embodiment, provides a high data density by being able to mount a number of data storage devices, such as disk drives, across the width of the system enclosure and provide the ability to access the devices via the front side of the enclosure. Presently, network attached storage devices employ enclosures that come in standardized widths that allow the system to be mounted in a rack that typically includes several other devices. The rack allows several systems or devices to be stacked one on top of another and thereby maximizes the use of available floor space in computer centers and the like. The invention includes a plurality of mounting bays that extend across the width of the enclosure. At least one of the mounting bays includes a rail that extends from either the top or bottom of the enclosure and a carriage for holding a data storage device, such as disk drive. The carriage includes a slot that is adapted to engage the rail in a sliding manner that allows a storage device that is attached to the carriage to be inserted into and removed from the enclosure via the front side of the enclosure. When a storage device is attached to the carriage and the carriage is engaged with the rail, at least one of the rail and carriage are substantially located between the storage device and either the top or bottom surface of the enclosure. In one embodiment, both the rail and the carriage are substantially located between the storage device and either the top or bottom surface of the enclosure. In the case of an 1U enclosure with a standardized width of approximately 480 mm, the mounting bay structure allows four, 3xc2xdxe2x80x3 disk drives (i.e. disk drives with 3xc2xdxe2x80x3 diameter disks but housings that have widths of approximately 4xe2x80x3) to be established across the width of the enclosure. Presently known network storage devices are only capable of placing three such disk drives across the width of such an enclosure. The mounting bay structure is readily extended to 2U and 3U enclosures that respectively have two and three times the height of a 1U enclosure. Consequently, a 2U enclosure can accommodate eight, 3xc2xdxe2x80x3 disk drives, and a 3U enclosure can accommodate twelve, 3xc2xdxe2x80x3 disk drives. The ability to insert and remove a carriage from the enclosure via an opening in the front side of the enclosure allows data storage devices to be moved into and out of the enclosure without having to remove the cover of the enclosure or otherwise disassemble the enclosure. Further, by avoiding such disassembly, the need to remove the system from any rack in which it is mounted is also avoided. Further, the carriage can be fixed in the enclosure with a latching system that relieves the user from having to use tools to install or remove the carriage.
Another embodiment of the invention is directed to a network attached storage system that is able to detect when a data storage device is likely to be removed from the system enclosure so that action can be taken to prevent the loss of any data being transferred to or from the device. In one embodiment, the system includes an enclosure, a mounting bay that includes a receiving structure and a carriage for holding a data storage device, and a latch which, in addition to allowing a carriage for a data storage device to be attached to and detached from the enclosure of the system, provides the ability: (1) to detect when the latch is being actuated by a user such that it is likely that the user is going to remove the carriage and any associated storage device from the enclosure; and (2) to produce a signal that allows remedial action to be taken to prevent the loss or corruption of any data being transferred to or from the storage device. In one embodiment, the latch includes a pin and an actuator that can be manipulated by a user to either engage the pin and thereby attach the carriage to the enclosure, or disengage the pin and thereby detach the carriage from the enclosure. Also part of the latch is a sensor that is capable of: (1) detecting movement of the actuator that is indicative of the possible removal of the carriage and any associated storage device from the enclosure; and (2) generating an electrical signal representative of the detected movement. Further, the sensor is adapted so that the detection of the noted movement and generation of the electrical signal occurs before any removal of the carriage and any associated storage device severs the electrical connections to the storage device, thereby allowing measures to be taken to prevent the loss or corruption of any data being transferred to or from the device. In one embodiment, the sensor detects the movement of the latch actuator between two points, both points associated with positions of the actuator where the storage device is still electrically connected to, for example, a buss card but indicative of the likely removal of the device from the enclosure. For instance, the first point could be a point at which the latch actuator has fully engaged the latch pin and the second point could be a point at which the latch actuator has only partially engaged the latch pin but at which the electrical connections to the storage device are still intact. In one embodiment, an electro-mechanical sensor is utilized that mechanically senses the change in position of the actuator and generates an electrical signal representative of the movement of the actuator that is indicative of the likely removal of the carriage from the enclosure. In another embodiment, an optical sensor is used to optically sense the change in position of the actuator and generates a signal indicative of a change in position of the actuator that is indicative of the likely removal of the carriage from the enclosure.
A further embodiment of the network attached storage system reduces or dampens vibrations that may adversely affect the operation of the data storage device or devices that are housed within the enclosure of the system. In one embodiment, system includes an enclosure, a mounting bay that includes a receiving structure and a carriage for holding a data storage device, and a vibration dampener for dampening vibrations between the carriage and the data storage device. In one embodiment, the vibration dampener includes an elastomeric mount that extends between the carriage and the data storage device. In one embodiment, the elastomeric mount includes a plurality of elastomeric tori. A hole in each of the tori accommodates a screw or other fastener that is used to attached the storage device to the mount. Each of the tori are also configured to be attached to the carriage. In one embodiment, each of the tori include a circumferential slit that engages an opening or notch in the carriage such that a first portion of the torus extends between the carriage and any data storage device and a second portion of the torus extends between the carriage and at least a portion of the screw or other fastener. In yet a further embodiment, the elastomeric mount includes a cylinder that is located within the hole of each of the tori and prevents the screw or other fastener from abrading the torus. In another embodiment, the vibration dampener includes two, torus-like structures that are connected to one another by a bridge. When the torus-like structures are engaging open-sided notches in the carriage, the bridge creates a tension between the two, torus-like structures that prevents the torus-like structures from slipping out of the notches. In one embodiment, each of the two, torus-like structures includes a flat side that is substantially flush with the edge of the carriage when the torus-like structures are seated in the notches. As a consequence, the torus-like structures occupy little, if any, of the space between adjacent carriages or between a carriage and a side wall of the enclosure.
Yet another embodiment of the network attached storage system attenuates vibrations that would otherwise be transmitted by the electrical connector or connectors that extend between a storage device in the enclosure and a buss card or other electrical device that is also located within the enclosure and communicates with the storage device. In one embodiment, the network storage system includes an enclosure, a mounting bay within the enclosure that includes a receiving structure and a carriage for holding the data storage device, and a vibration dampener that includes an electrical connector that extends between a data storage device and a buss card or other electrical device. In one embodiment, the electrical connector includes an electrical conductor that incorporates a U-shape that serves to dampen vibrations between the storage device and the buss card or other electrical device. In yet another embodiment, a plurality of flat cable connectors are utilized that contribute to the dampening of vibrations. Another embodiment combines the vibration dampening provided by the electrical connector and the vibration dampening provided by the elastomeric mount to substantially isolate a storage device from all the likely sources of vibration, namely, vibrations transmitted by the enclosure through the mounting structure and vibrations transmitted through the electrical connections between the storage device and its associated buss card.
Yet another embodiment of the network attached storage system provides the ability to readily accommodate types of storage devices that have electrical interfaces whose locations vary from manufacturer to manufacturer. For example, IDE disk drives must conform to an industry specification requiring two electrical interfaces located on the back wall of the drive, one for transmitting power to the drive and the other for transmitting data between the drive and a buss card. However, the specification does not require the connectors to be placed at any specific locations on the back wall of the drive. Consequently, there is substantial variation in the locations of these interfaces from manufacturer to manufacturer. One way to accommodate this type of variability in the location of the electrical interfaces in a network attached storage system is to provide separate buss cards for each variation in the location of the electrical interface. Consequently, if one storage device is replaced with another storage device that has an electrical interface in a different location, the old buss card is replaced with a new buss card that has an electrical interface that is positioned to mate with the electrical interface of the new storage device. The present invention, however, avoids the need to replace the buss cards. In one embodiment, the network storage device includes an enclosure, a mounting bay that includes a receiving structure and a carriage for accommodating a data storage device with an electrical interface, and an intermediate electrical connector that is associated with the carriage and capable of accommodating the noted variation in the position(s) of electrical interfaces(s). In the case of IDE disk drives, an electrical connector is provided that includes first and second connectors for respectively engaging the data and power interfaces of the drive, a third connector for engaging the buss card, and two flexible electrical conductors that extend between the first and second connectors and the third connector with at least one of the electrical conductors including a plurality of electrical conductors that are separated from one another. The flexible connector associated with the connector that engages the data interface of the drive includes a plurality of flat cable conductors. The plurality of flat cable conductors allow the connector to be readily positioned to accommodate variations in the positions of the data interface, especially when conductors are relatively short (e.g. a few inches). Moreover, the plurality of flat cable conductors also facilitate the attenuation of vibrations that could otherwise adversely affect the performance of the data storage device. In one embodiment, the plurality of flat cable conductors are realized by splitting a single, multi-conductor flat cable, except for the ends, which are attached to connectors In operation, the first and second connectors can be positioned to address variations in the positions of the power and data interfaces on the IDE disk drives of various manufacturers. The third connector, however, remains substantially stationary but positioned so as to interface with the electrical interface of the buss card. In one embodiment, the flexible electrical conductor incorporates a U-shape that contributes to the attenuation or dampening of vibrations that could adversely affect the operation of a data storage device associated with the carriage.